I still don't know how much shipping is going to cost, so I've just assumed that $16/motor + taxes = £16/motor. I've also just assumed that 10 PCBAs (including passives) would be £5.50 for now.

The motor part costs £20 and the ESC circuitry costs another £9. Looking at prices for the latter, it's probably respectable considering the feature list.

For ease of assembly, I've gone with a seemingly decent -26dB microphone from JLC's part list. It also costs 60p more, but I'm going to use the QFN package of the magnet sensor for the time being for the best chance of everything fitting.

I am also researching into O-rings and asking if the rotor bearings can be made waterproof. Why? Because Tetent and Tetinerary are expensive and I can't just RMA it or Amazon up a new one if a spill happens, nor do I want to have to live a life of babying the device.

I happened to find a 15mm diameter BLDC that is used for RC cars. The other 15mm I found is called the 1410 and it's a similar size but the winding offerings are slightly different. The exploded view at least gives me some confidence that my motor design isn't doing anything out of place. The rotor is only 6mm diameter by 14.5mm long, however, as well as 2 pole.